Bleaches are used for various purposes such as deodorization, stain removal, brightening, whitening, disinfection, sanitizing, sterilizing, and the like. Bleaches are used to treat various substrates, including hard or non-porous surfaces, soft or porous surfaces and materials such as fabrics, textiles and clothing, by various means including wetting, wiping, spraying or immersion in bleaching solutions or their aqueous diluted forms, for example. Aqueous bleach solutions based on oxidants such as a hypohalous acid or peroxide are commonly employed for this purpose. For best results, the bleach solutions are employed soon after preparation when oxidant levels are at their highest level in order to achieve optimum bleaching action for the purpose desired. Commonly, however, bleach solutions are stored for prolonged periods between uses, and under conditions that may result in a loss of oxidizing strength that can reduce performance significantly over time. Storage factors such as time, temperature, packaging and exposure to light can decrease the stability of aqueous bleaches. In addition, other materials present, such as dyes, thickeners, polymers, dispersing agents and the like can also act to decrease the stability of aqueous bleaches and themselves be subject to the oxidative action of the bleach, resulting in substantially reduced performance and poor product characteristics.
One approach in the art to minimize performance loss is to incorporate materials in the form of solids in particle form to reduce interaction with the oxidant. Generally, such particles are limited to chemically stable materials that are themselves bleach resistant or have minimal effect on the oxidant stability. However, additional stabilizing and/or dispersing agents are required to overcome the otherwise inevitable physical instability that results from settling, aggregation and/or precipitation of such particles over time. Typically, dispersing and stabilizing agents act to suspend the particles against aggregation and settling, and achieve this by means of thickening, viscosity modification or network formation that tend to alter the rheology of the bleaching solutions. Thickened bleaches and bleaching gels are common examples of the resulting rheologies required when particulate coloring agents are used. The changed rheologies of the bleaching solutions results in changes to the processing, handling, pouring and dispensing characteristics, which limits their utility in certain applications, such as in spraying and dosing applications. Further, the additional materials added can negatively impact stability and add cost to the bleaching solutions.
In light of the foregoing discussion, there is a need for stable aqueous bleaching solutions having optically functional particles for providing functional benefits to the bleaching solution and substrates treated with the bleaching solution, where stable The aqueous bleaching solution should provide means enabling a stable suspension of the optical functional particles, and needs to be resistant to chemical degradation in the presence of an oxidant. Further, the aqueous bleaching solution should be stable without the requirement of using thickening agents, flocculants and/or dispersing agents and the like.